Over the last decade, video games have been a popular form of entertainment for consumers. As the computation necessary to generate advanced full-motion graphics has steadily become cheaper, and algorithms for generating imagery on the fly have become more well developed, the average consumer has continued to make regular expenditures of discretionary income to upgrade home video game systems, and play the latest arcade video games. One of the draws of arcade video games and advanced home video games is the level to which the realism of the images enables the player to escape from the real world for a time and enter the fantasy world of the game. The graphics of top arcade games have gone from simple two-dimensional representations, to three dimensional representations with complex shading and textures, and the laws of physics well represented in how the three-dimensional characters and objects in the games interact.
As the video images produced by top video games have taken staggering leaps forward in complexity over the last ten years, the sound tracks of these games have also advanced considerably, though not as much as the video images have advanced. This is partly due, perhaps, to the lack of significant advancement in the designs of the speaker systems that deliver the sound to the consumer who is playing the game. Most speaker systems in arcade video games remain quite similar to those of 10 years ago. These are either simple monaural speaker systems, or simple stereo speaker systems, usually mounted in the cabinet of the video game console, which is usually positioned in front of the consumer playing the game.
As the sound tracks for these video games improve, they are getting closer to the level of quality found in the sound tracks of today's box office hit movies. These movies often contain amazing special effects. A sound track which creates an acoustic experience which "grips" the audience can be a key factor in transporting the audience into the artificial reality being created by the movie. In this vein, top-of-the-line video games will be using sound more and more to create the reality for the player of the game. As this trend continues, it is likely that audio systems for video games are likely to continue to improve in quality. Let's take a look at the nature of the "quality" that home audio system designers have striven for over recent decades.
The reproduction of music, with desirable psycho-acoustical characteristics (such as might be experienced in a concert hall listening to a live performance) has been the objective of many in the audio industry for years. The modern pursuit of this goal has included implementations utilizing digital signal processing for the reconstruction of a sound field by measuring the acoustic response of the field and then modifying the input to an array of loudspeakers to produce the appropriate velocity and pressure within the fluid medium.
Some hold that audio systems should be designed for the "exact" reproduction of a sound field that might be experienced by a listener in a concert hall. The exact reproduction of a sound field can be approached one of two ways. In the first way, a recording of the sound experience to be reproduced may be made on a binaural recording device which mimics the size and shape of a human head (including the ears). When played back through headphones, such a recording can be strikingly lifelike, with much of the spatial (directional) cues preserved. The disadvantage of this type of recording is that it is so highly optimized for headphone play-back; it does not sound as good as a "regular" stereo recording when played back through speakers which aren't right next to the listener's head. Another disadvantage of headphones is that their use may be cumbersome or impractical in some applications, and headphones used in public applications (such as in CD stores or arcades) are prone to reliability problems.
The second way that one can approach the reproduction of a sound field is to produce a sound field with multiple speakers placed at different points in space, and fed different signals (hereinafter referred to as a "multi-channel" audio system). Stereo is the simplest such commonly employed approach. Such psycho-acoustic parameters as perceived "depth", "spaciality", "color", and "timbre" are generally agreed to be much improved in a stereo sound system, as compared with a monaural sound system. Driver characteristics such as linearity and frequency response also affect the perceived quality of the signal.
Sound systems with more than two speakers also exist (though they are not as widely used as simple stereo). Such systems include Dolby Surround-Sound (used in theaters), and earlier attempts at "quadraphonic" standards. The problem in designing multiple-speaker systems beyond simple stereo is choosing a trade-off in the number of transducers, the placement of those transducers, the design of those transducers, and the signals fed to those transducers to economically produce a "desirable" psycho-acoustical effect.
Trying to recreate a standard audio bandwidth (20 Hz-20 kHz) sound field to arbitrary accuracy throughout a room is a totally impractical problem. As detailed in a publication by Nelson, P. A., 1994, "Active control of acoustic fields and the reproduction of sound," Journal of Sound and Vibration, 177(4), pp. 447-477, to identically reproduce a sound field with an array of transducers over a frequency range extending from 20 Hz to 10 kHz and for a sphere of 10 m diameter would require over 1 million individual sources.
Fortunately, the human auditory system is not measuring "everything" about the sound field. Some is known about what "key" things contribute to perceptions (perceptions such as "this sounds `real`, and this doesn't"), and a lot is still not known. An exciting opportunity exists in the field of audio to discover and design systems which, while much simpler than the above described one million transducers, provide highly desirable psycho-acoustical effects at reasonable prices, and are thus valued by consumers.
One cost-saving innovation which has become quite widespread in modern stereo systems is the addition of a third "subwoofer" transducer to the original stereo model. The sub-woofer produces low-frequency sounds, usually below about 250 Hz. The human auditory system is not good at determining the source direction of such low-frequency sounds. Thus one transducer may be used as effectively as two, an the sub-woofer transducer may be placed anywhere in the room. In typical musical selections, these low frequencies account for most of the power that a loudspeaker set requires. They also account for most of the distance of cone-motion in loudspeakers. By removing the low frequencies from the stereo speakers, cone motion, and its associated nonlinearities (which cause distortion) are reduced. All these factors together allow the stereo speakers (in a system utilizing a subwoofer) to be manufactured in smaller, less obtrusive enclosures, with cheaper components, for less cost. The consumer gets a higher quality, more aesthetically pleasing system, for less money.
Within stereo systems (with or without sub-woofers), the mid and high frequencies are often produced by separate transducers in the same cabinet (so-called "midrange" drivers and "tweeters"). While often not necessary from a distortion perspective, the splitting of mid and upper-range frequencies between two transducers is often desirable from the standpoint of obtaining a flat frequency response. Mid-range drivers often have numerous high frequency resonances, at which the amplitude of sound produced changes drastically. This produces a sound of less desirable quality. Another problem with mid-range drivers at high frequencies is that they typically produce widely varying sound intensities in different directions, thus, depending on where the listener is in the room (worse yet, if the listener is moving in the room) the listener may hear inconsistent or annoying quality variations from the speakers.
In the past ten years, signal processing, and in particular, digital signal processing has allowed for the most significant breakthroughs in the quest for more psycho-acoustically pleasing sound reproduction. The quest for "accurate" reproduction of sound is ironic in some ways. Many have been assuming the need to accurately reproduce something, yet concert halls with the same (accurate, live, "real") sources in them have vastly different perceived qualities, even with no distortion. Taking this into account, one could hold that an ideal audio system could create new realities (or acoustic environments), not just reproduce known ones. Some of today's digital signal processing units have taken a cut at creating part of the reality (as the concert hall does). Digital signal processing audio units cannot, however, overcome some of the basic physical limitations imposed by the speakers we attach to them, such as the physical positions of the speakers in the room, and their directionality (radiation patterns) at different frequencies.
We are a society undergoing a paradigm shift in our culture regarding entertainment. Today's movies and virtual reality games take us well beyond the thirst for reality in reproduction, into a thirst for things beyond what are "real", the thirst for new experiences which can be created. Musicians electronically create instruments that do not exist, which have pleasing musical characteristics. Special effects experts create entire visual worlds that do not (an indeed in some cases cannot) exist, and people pay higher and higher prices to experience these creations. Many of these creations put the observer in places where he or she cannot normally be ("in the experience", so to speak), such as standing next to a Tyrannosaurus Rex as it eats someone. The desire here is for the new, the vivid, the "more than real", but definitely not just "accurate reproduction of something previously experienced".
As the demand for the ability for us to "enter the experience" grows, a significant market will form for in-home systems which can provide this "more than real" entertainment. New acoustical sound production paradigms (not just sound reproduction, because we want to make things "more" than real) will be in demand.
It is an object of the present invention to provide an improved multi-channel audio system which, when playing today's film and video game sound tracks, provides a more involving "gripping" psycho-acoustical experience for the listener, transporting the listener more effectively into the virtual "reality" of the film or video game. It is a further object of the present invention to provide an improved multi-channel audio system which is superior to present-day stereo and other multi-channel audio systems, in such psycho-acoustical dimensions as "timbre", "color", "spatiality", and "depth". It is a further object of the present invention to provide an aesthetically pleasing, ergonomically superior multi-channel audio system. It is a further object of the invention to provide a multi-dimensional acoustical audio system that combines the selection of transducers, the placement of those transducers and the spectral separation of frequency to the transducers to optimize the psycho-acoustical effect to the user. It is a further object of the invention to provide the psycho-acoustical experience to the user with a focus on the binaural auditory system and tactile sensory system of the user and not the audio source. It is a further object of the invention to provide an easy-to-set-up, easy-to-store, portable seat for use with video games and the like, with integral sound and/or vibration which provide an enhanced virtual reality experience.